Pulp-screening machine



Jan. 7, 1930. A. J. HAUG 1,742,592

PULP SCREENING MACHINE Filed April 23, 1927 2 Sheets-Sheet 2.

chines of the centrifugal type.

Patented Jan. 7, 1930 i NiTEDi srA ANTON" aosnrnnAue, or NASI IUA, nnw'nnnrsnrnn I 'rULr-jsonEEnInG 'M'AcHInE This invention relates to machines for screeningpulp of-the character produced in the paper making lIlClllSlZ-TY and is more. especially COI1CII1Cl"W1th pulp. screen ng. Ina

It is the chief object of the invention to improve pulp screening machmes with a V1W- to devising a machine whichwill effect abetter separation of the good pulp from the lo coarser materials or tailings'which are rejected by the screen." The invention deals especially withthe treatment of the tailings during and immediately after the pulp screening operation.

understood from the following description when read in connection with the accompanying drawings, and the novel features will be particularlypointed out in the appended claims. F

'In'the drawings,

Figure 1 is an end View of a pulpscreening machine constructed in accordance with this invention;

Fig.- 2 is a vertical cross-sectional VIlGW' I through the casing and screen drum of the machine shown in Fig. 1, the impeller being shown in elevation; f r

Fig. 3is a cross-sectional view on the line 33, Fig. 1; j

Fig. 4 isan end view showing a modified construction and Fig. 5 is a vertical cross-sectional view of substantially the construction shown in Fig. 4.

Referring first to Figs. 1, 2 and 3, the screening machine there shown comprises a casing 2 in which is mounted a screen drum which preferably is cylindrical in form and is supported in a stationaryposition, al

though it may be rotatedifdesired. The;

The nature of'theinvention'will. be readily 1327. :Serial No. 186,015.

disk-like head 6 at the end of the inner wan. The stock so admitted to the screenchamber is immediately acted upon by a rotary imipeller 7 provided withblades' 8, this impeller being mounted on a horizontal shaft '9 which is supported insuitable bearings carried by the machine casing] A 'pulleylO is secured-to this shaft so-that it may be belted to'any'con venient source of powerf This impeller revolves rapidly and it sets up sutficientcentrifugal force in the incoming pulp to: force the greater part of the pulp'through the screen 3v immediately after it has entered the screen chamber.

The tailings -o r in other words materials which cannot pass through'the screen, "are urgedalongthe surface of the screen toward theendthereof opposite to the pulpinlet bv the impeller blades 8, these blades being slightly inclined-with reference to'their axis of rotation,fas clearly shown in Fig. '2, in

order to produce this action-.1 The screenedpulpfiows out .of the casing almost imme diately through the pulp outlet 12, Fig; 1,

which'leadsfrom the-bottom of the casing, but the 'ta'ilings are transferred relatively slowly acrossthe surface of the "screen. Shortly before theyare ejected from} the screen they are washed by a shower of water flowing through the annular outlet13 from the chamber 14 which iscored'in'thecasing 2,

water-being delivered to this chamber'by a pipe15i The tailings finally are'discharged througha tailings conduit or spout 16-.

It should be noted that-this spout or conduitleads out of the screen chamber at the upper side thereof and considerably above the i axis of the impeller. Thislocation of the j spout makes it necessary to lift the taili'ngs into' the spojut and imposes certain back pressure or resistance to the ejection ofv the l tailiIigS-i @The arrangement thus results in liolding thetailings inthe 'screenchamber for l a considerably longer time than has been cu's- I tomaryinmachines of'this type; and this fact togetherwith the washing of the'tailings-im-; mediatelybefore they are ejected from the screen; results in a more nearly complete separation of the good stock from the 'tail ings. A-further advantagederived from'this' arrangement is the fact that the tailings are discharged from themachine at such a level that they can be delivered directly to a subsequent machine which is to act on them without the necessity for pumping or otherwise elevating them. j

As shown in Figs. 1 and 3, a pipe 17 is connected into the tailings-outlet so that if clesired, a stream of water can be directed into the tailings parallel to their line of move- ,ment as they are discharged through the outlet 16, thus facilitating the discharge of the tailings and their delivery to the machine or. I

, ingpulp into said drum, means independent apparatus which is to receive them.-

It will beobserved that the ejection of the tailings from the casing of. themachineis produced partly by the centrifugal action of the impeller blades on thetailings. Thisaction is made more pronounced in the construc- ,tion shown in Figs. 4 and 5.. The machine shown in these figures is like that shown in Figs. 1 .and2 except for the fact that the right-hand end, Fig.5, of the casing is provided with an annular tailings chamber 18, andthe impeller blades 8' are provided at their right-hand ends with wings or extensions 19 which project into said chamber 18. These blades thus act on the tailings, first to eject them from the screenin the same man ner describedin connection with Figs. 1 and 2, and thereafter the wings 19 act centrifugally on the tailings to force them out of the discharge spout 20, Fig. 4. In this machine, as in that previously described, the tailings unust be lifted into'an elevated position in order to eject them, and the heighttowhich they are lifted can be made even greater than that shown ,in Fig. 4., if desired. In both cases the tailings are discharged in a continu- 0; ions stream, and in the construction shown in Fig. 4 a very substantial head of tailings continuously opposes the action of the impeller,

wings 19 in, forcing the tailings out of the machine casing. The tailings therefore are retained in the screen for a relatively long period andbefore they leave the screen they are 1 washed by the shower directed through the annular opening- 13 so thatgan unusually efsuch as that shown at'11, Fig. 2, which will run in the opening 13 and thus clear out mechanicall any accumulations that otherwise,

would collect in it. I

YVhileI have herein shown and described preferred embodiments of my invention, it

will beunderstood thatthe invention may be I 1. In a pulp screening machine, the combinationofascr'een drum, means for conductofsaid' drum for creating centrifugal force in'thepulpto impel it through the screen, ro-

tary means for acting centrifugally on the tailings rejected by the screen to eject them from the-screen, and a discharge conduit extending above the levelfofthe top of the. drums into which the tailings are lifted and through which they are forced by said rotaryv means. j g l v 2. In a pulpscreemng mach1ne,the combi nation of a screen drum, a casing in which said screenis mounted, means fo r conducting pulp into said screen, v a rotary. impeller mounted in said screen for creating centrifugal force in the pulp to force it throughthe screen, said impeller having blades serving to force the tailings rejected by the screen along the surface of the; screendrum toward the tailings discharging end thereof and includ-- ing parts serving to act on the tailings after leaving said drum to ej ect them from the casing, and a conduit for conductingthe tailings upwardly from said drum and through which said tailings are discharged by said impeller. v V

ANTON JOSEPH HAUG.'

fective separation of the good stock from the tailings is produced.

It has'been common in pulp screens of this type to provide a water chamber somewhat like that shown at 1 1 and to discharge the water from this chamber into the screen through aseries of holes. Frequently the water-used for this purpose has previously been used at some other point in the pulp making process and therefore contains some-pulp fibre or other materlals in suspension. There 18 considerable danger, therefore, thatthis suspended material will plug the holes. This danger is reduced Icy-making theoutlet or discharge for the water in the'form of an annulus, as shown. I, prefer, also, to provide onev I 'or more of the blades 8 with a pin or finger, 

